2 research outputs found
Polymorphic Layered MoTe<sub>2</sub> from Semiconductor, Topological Insulator, to Weyl Semimetal
Large
size (∼2 cm) single crystals of layered MoTe<sub>2</sub> in
both 2<i>H-</i> and 1<i>T</i>′-types
were synthsized using TeBr<sub>4</sub> as the source of Br<sub>2</sub> transport agent in chemical vapor transport growth. The crystal
structures of the as-grown single crystals were fully characterized
by X-ray diffraction, Raman spectroscopy, scanning transmission electron
microscopy, scanning tunneling microscopy (STM), and electrical resistivity
(ρ) measurements. The resistivity ρ(<i>T</i>), magnetic susceptibility χ(<i>T</i>), and heat
capacity <i>C</i><sub>p</sub>(<i>T</i>) measurement
results reveal a first order structural phase transition near ∼240
K for 1<i>T</i>′-MoTe<sub>2</sub>, which has been
identified to be the orthorhombic <i>T</i>d-phase of MoTe<sub>2</sub> as a candidate of Weyl semimetal. The STM study revealed
different local defect geometries found on the surface of <i>2H</i>- and <i>T</i>d-types of MoTe<sub>6</sub> units
in trigonal prismatic and distorted octahedral coordination, respectively
Proximity-Induced Superconductivity and Quantum Interference in Topological Crystalline Insulator SnTe Thin-Film Devices
Topological
crystalline insulators represent a new state of matter,
in which the electronic transport is governed by mirror-symmetry protected
Dirac surface states. Due to the helical spin-polarization of these
surface states, the proximity of topological crystalline matter to
a nearby superconductor is predicted to induce unconventional superconductivity
and, thus, to host Majorana physics. We report on the preparation
and characterization of Nb-based superconducting quantum interference
devices patterned on top of topological crystalline insulator SnTe
thin films. The SnTe films show weak anti-localization, and the weak
links of the superconducting quantum interference devices (SQUID)
exhibit fully gapped proximity-induced superconductivity. Both properties
give a coinciding coherence length of 120 nm. The SQUID oscillations
induced by a magnetic field show 2π periodicity, possibly dominated
by the bulk conductivity